Answer:
30 seconds
Step-by-step explanation:
The first puppy is running at a rate of 4 feet per second; letting t represent the number of seconds, this is 4t.
The second puppy is running at a rate of 5 feet per second; this is 5t.
In order for them to be 250 feet apart, they would have run 520-250 = 270 feet.
Together their combined distances will be 4t+5t, and it will equal 270:
4t+5t = 270
9t = 270
Divide both sides by 9:
9t/9 = 270/9
t = 30
It would take 30 seconds.
The first puppy would travel 4(30) = 120 feet, and the second puppy would travel 5(30) = 150 feet; this is a total of 120+150 = 270 feet. This leaves them 520-270 = 250 feet apart.
